in South Africa document increasingly sophisticated tool technology. At these two sites, Blombos Cave and Klasies River Mouth, ancient hunters had learned how to convert flint nodules into many more inches of long, sharp blades by using a hammer of softer and more controllable material. They turned some of those blades into scrapers for freeing animal hides from fat. They used chisel-like flints to make slots in bone or wood so that tools could be set more efficiently in a handle. They sharpened bone splinters into awls for perforating hides, allowing for tailoring with string or sinew. They also produced tiny flints that served as barbs for composite weapons.
As early as 80,000 to 70,000 years ago, from Morocco in the north to Blombos Cave in the south, ancient humans had begun drilling seashells to string on necklaces and were decorating themselves with red ocher and white pipe clay, two naturally occurring pigments.
While the humans of 1.8 million years ago had concentrated much of their effort on procuring large-game animals, our more recent ancestors had broadened their idea of food to include fish, perhaps because they now had string for making nets. And one of their most significant improvements in food procurement was recorded at Klasies River Mouth, in archaeological deposits dated from 75,000 to 55,000 years ago.
Klasies River Mouth lies in a zone of vegetation that today’s South Africans call fynbos (literally, “fine bush”). Included among the plants of the fynbos is a flower called watsonia, a member of the lily family. Like its relative the gladiolus, it has a sizable corm, or bulb, which in the case of watsonia is edible. When fynbos vegetation is deliberately burned off, watsonia grows back with its density per acre increased five to ten times. It seems that the occupants of the region had discovered that fact, because some archaeological layers at Klasies River Mouth have dense accumulations of burned watsonia and other fynbos plants.
What is exciting about this discovery is that it reveals the people of that era to have had what economists would call a delayed-return strategy. Rather than restricting themselves to plants or game whose harvest yielded immediate food, the occupants of Klasies River Mouth were willing to invest labor in activities that would yield no food until the next growing season. At that future time, however, their effort would be rewarded by a harvest five to ten times larger than before. To state it differently, some early humans had learned not merely how to take food out of the environment but to engineer the environment itself. Almost certainly they were able to do this because they had become astute observers of nature and, like the nineteenth- and twentieth-century hunter-gatherers studied by anthropologists, could name hundreds of plants and animals and rattle off the details of their habitat preference and behavior.
From that point on, the evidence for human interference in the environment, sometimes called “ecological niche construction,” is repeated at other archaeological sites in widely scattered regions.
Consider, for example, the following case. In the Egypt of 20,000 years ago the level of the Nile River was 50 feet higher than today’s—and rising. At flood stage its surge of water, carried north toward the Mediterranean from Lakes Victoria and Albert, was sufficient to drown the arid canyons that entered it from the Egyptian desert. Just north of present-day Aswan, a dry canyon known as the Wadi Kubbaniya enters the Nile from the west. From June to September the flooding Nile backed up into the canyon’s lower course, submerging all but its tallest sand dunes. This flooding created a rich, localized environment where catfish and tilapia gathered and where water-loving plants like sedges and rushes grew abundantly.
Such is the clamor of spawning catfish that their mouth-and-tail slapping can be heard hundreds of yards away. That sound is probably what